Heat treatment of cables



Jan. 9, 1934. R. o. HELGEY 159421550 HEAT TREATMENT OF CABLES Filed Nov. 9, 1951 y am Patented `Ian. 9, 1934 1,942,550 HEAT TREATMENT F CABLES Ralph ognelgeby, Flint, Mich., assignor to A c Spark Plug Company, Flint, Mich., a company of Michigan Application November 9, 1931. Serial No. 573,871

4 Claims.

This invention relates to flexible cables or shafting and has particular reference to the flexible cables used to drive speedometers of automotive vehicles.

In the manufacture of flexible shafting, a plurality of windings of wire is placed over a core wire. In making the shaft entirely of steel wires, it has been found that the windings on the shaft caused a stiffness therein which produced what is known as whip when the cable was in use. This whip is objectionable and in an endeavor to remove it, the core wire and first winding have been made of phosphor bronze wire. The phosphor bronze wire was more expensive than the steel wire and necessitated the carrying in stock of two different kinds of wire.

It was found that if the finished cable is given a heat treatment by passing it through a furnace while under tension and the cable then cooled and run in an oil bath that the whip Was substantially'eliminated Without interfering with the strength or life of the cable. The essence of the invention therefore consists in heat treating the flexible shafting by causing it to pass through 25 a furnace while under a stretch or tension and thereafter allowing the cable to cool. The passing of the cable through the oil bath may be omitted.

On the drawing: 30 Figure 1 shows a portion of apparatus for heat treating the cable.

Figure 2 is a continuation of the structure of Figure 1.

Figure 3 is a side View of a portion of Figure 2 showing the oil bath and the weight to tension the cables.

Referring to the drawing, the numeral 2 indicates a carriage on which there are mounted the reels or spools 4 containing the flexible shafting 6 as it comes from the cable winding machine. The spools are preferably mounted in-pairs with the end of the shaft on one spool tied to the end of the second so that the two may be passed through the apparatus together. From the spools 4 the shafting 6 is led over the guide pulleys 8 on to the pulleys 10 which are spaced apart substantially at equal distance. The pulleys 8 and 10 are mounted in the frame 12 which also has the further guide pulleys 14 at one end thereof to direct the shaft-l resistance wire receiving electric current from the Wire 26. The heating or resistance wire 24 is preferably ycovered with alundum cement to keep the wire separated and the space between the resistance wire and the shell 16 is preferably packed 60 with a heat resisting substance of any suitable kind. The cables 6 enter the furnace 16 at the end indicated at 28 and leave it at the end 30.

From the furnace 16, the cables pass through a cooling tube 32 which may be of any suitable con- 65 struction and which preferably has a blast of air forced therethrough, such as by a fan (not shown). The cooling tube is supported by a trough 33.

From the cooling tube the wires pass over pulleys 34 and 38, the pulleys 38 having weights 36 attached thereto, one weight to each pair of cables. From the pulleys 38, the cables pass over the pulleys 40 and 42 into an oil bath 44 having the pulleys 46 or a roller mounted therein. The cables then pass over the pulleys 48 to the directional spools 50 and to the guide wheels 52 mounted on the shaft 54 in a frame 56 at one end of the machine. From the guide wheels v52 the pairs of cables 'are broken and the cables 6 pass directly to the reels 58 on which they are wound.

The mechanism is driven by means of an electric motor 60 mounted on the frame 56 and having the shaft 62 driving the gearing 64. Suit- 85 able chains 66 are interconnected with the shafts 54 and rollers 68 to drive the same. The driving of the rollers 68 willrotate the reels 58 to cause them to wind the vcable 6 thereon. An automatic feed 69 winds the cable in even windings 90 on the reels 58.

In the heat treating of the cable,'is is preferred to have the weight 36 of a size that it will put a tension of about 9 lbs. on the cable when it is travelling about the rate of 21 feet per minute'. 95 With a cable travelling at this rate, it is desirable to have a furnace of about 10 feet in length and the rate of travel of the cable is so fixed that it will remain in the furnace a suiciently long period of time to heat it to a dark straw color.' A temperature of about 560 at the entrance end 28, 510 at the middle, and 570 at the exit end 30 is desirable, the degrees being according to the centigrade scale. These precise degrees of heat are not absolutely necessary as a variation of some degrees either Way will give equally satisfactory results.

In passing the cables from the reels 4 through the directional and guide rollers on the frame 12, the directional and guide rollers 8, 10 and 14 may 1N have considerable friction therein so that some pull is required to draw the cable therethrough. Or optionally, a suitable clutch is incorporated with each pulley 10 sothat when the weight 36 at the end of the machine is lifted due to rapidf Winding, the clutch is released so the pulleys 10 become loose and the cable slips, thus releasing the Weight to its normal position. When the weight is released, the clutch is thrown in and the cable pulled again.

The heat treating of the cables in accordance with the above-described process eliminates about 85% of the Whip and decreases the internal friction by about 60%.

I claim:

l. The method of removing stiffness and internal friction from multistrand wire exible shafting for driving speedometers and the like, consisting of passing the shafting through a heated furnace having altemperature of substantially 560 C. at its entrance, substantially 510 C. at its middle and substantially 570 C. at its end.

2. The method of removing stiffness and internal friction from multistrand Wire flexible shafting for driving Aspeedometers and the like,

consisting of passing the shafting at a rate of substantially 2l feet per minute through a heated furnace substantially ten feet long and having a temperature of substantialy 560 C. at its entrance, substantially 510 C. at its middle, and substantially 570 C. at its end.

3. The method of removing stiiness and internal friction from multistrand wire cables consisting of passing the cable through a heatedY furnace having a temperature of substantially 560 C. at its entrance, a slightly reduced temperature at its middle and substantially 570 fC. at its end.

4. The method of removing stiiness and internal friction from multistrand Wire cables consisting of ypassing the cable through a heated furnace having a temperature of approximately 560 C. at its ends and a slightly reduced temperature at its middle.

RH O. HELGEBY. 

